Method of coating



May 27, 1924.

1,495,487 J. B. JOHNSON METHO/D/OF COATING Filed Dech 28, 1 922 hven/bna/o/m 5. Johnson.

drawn from the bulb by suction Patented May 27, 1924.

UNITED STATES PATENT OFFICE.

JOHN IBERTRAND JOHNSON, OF ELMHURST, NEW YORK, ASSIGNOR 'I'O WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, Y., A CORPORATION OF NEW YORK.

METHOD OF COATING.

Application filed December 28, 1922. Serial No. 609,382.

To'all cvhom it may concern:

Be it known that 1, JOHN B. JOHNSON, a citizen of the United States, residing at Elmhurst, in the county of Queens, State of New York, have invented certain new and useful Improvements in Methods of Coating, of which the following is a full, clear, concise, and exact description.

This invention relates to the art of coatin and has as its object the application of a uorescent coating to the interior of a glass bulb adapted for use as the envelope of an oscillograph tube.

According to this invention, the bulb is thoroughly dried and that portion of the bulb to be coated is moistened with an adhesive material. The material of the coat ing is reduced to a very fine powder and is introduced within the bulb in the form of a dust cloud from which the material settles on to the adhesive material to former coating.

Referring now to the drawings, Fig. 1 dis closes the bulb to be coated and one of the tools used in the process, and Fig. 2 discloses the bulb and another tool used in the process.

The bulb 10 is first thoroughly cleansed and dried after which it is placed in the 0- sition shown in Fig. 1. A weak, prefera ly 10% solution of sodium silicate 11 is introduced into the tube in a suiiicient quantity to cover only that portion of the tube which is to be coated. The sodium silicate is then removed my means of the tool 12 shown in Fig. 1 into which the li uid is om a water aspirator. After the liquid is apparentl all withdrawn, the bulb is allowed to stan for a short time to permit all surplus remainin liquid to flow to the center of the bulb a er which the suction tool is again utilized to remove any surplus.

The fluorescent powder used for the coating preferably comprises a mixture of equal ,dium silicate. The tool used for forming the dust cloud comprises a tubular member 14 having attached to one end a cylinder 15 of fine mesh linen gauze and a cup-shaped member 16 attached to the other end of the gauze. At the upper end of the tool is provided a rubber bulb 17 adapted to receive the powder and to the bulb is attached a tube 18 of very small diameter which is arranged within the tubular member and extends into the cup-shaped member. A supply 19 of powder -is placed in the bulb and is blown a ainst the bottom of the cup by squeezing t e bulb. The'powder is deflected upward from the bottom of the cup and forced out throu h the mesh in the gauze to form a dust clou which is allowed to settle.

Suficient powder is dusted or sifted into the bulb toproduce a white even coating and heavy enough so that the powder, when viewed on the interiorof the bulb does not have a wet or glossy appearance. The bulb is then'dried for about ten minutes after which it is laced in an oven, the temperature of whic is gradually raised to 400 degrees centigrade. The bulb is baked at this temperature for about ten minutes, after which it is cooled to room temperature and the loose surplus powder removed from the bulb by means of a felt swab or the like.

In carrying out this process, care must be taken that the film of sodium silicate left on thebottom of the tube be of uniform thicle v ness and that there be no drops of silicate on the sides of the tube. Furthermore, the thickness of the film should'be such that the particles of fluorescent powder are not covered by nor saturated with the sodium silicate.

lit is, of course, understood that various materials other than those specifically mentioned may be utilized in this process without in any way departing from the s irit of the invention, as set forth in the to lowing 95 claims.

The invention claimed is:

1. The method of coating a vessel which comprises applying an adhesive to the inner wall of the vessel to be coated, introducing into the vessel a finely powdered material in the form of a cloud, and allowing such ma terial to settle on the adhesive.

2. The method of applying a fluorescent coating to the bulb of an oscillograph tube m5 which comprises applying an adhesive to in the form of a dust cloud and allowing the coating material to settle on the adhesive.

8. The method of applying fluorescent ma terial to the interior of the bulb of an oscillograph tube which comprises applying. an adhesive to that portion of the bulb to be coated, spraying the coating material into the bulb in the form of a dry powder and allowing said powder to settle on the adhesive.

4. The method of applying fluorescent material to the interior of a bulb of an oscillograph tube which comprises applying an adhesive to tha portion of the bulb to be coated, spraying a fluorescent powder into the bulb in an upward direction and allowing the powder to settle.

SrThe method of applying a fluorescent coating to the interior of the bulb of an oscillograph tube Which comprises applying means? an adhesive to that portion of the tube to be coated and dusting the fluorescent material onto the adhesive in the form of a dry powder..

6. The method of applying a fluorescent coating to the bulb of an oscillograph tube which comprises applying an adhesive to that portion of the tube to be coated, introducing into said tube a supplyof powdered fluorescent material in the form of a dust cloud and allowing said material to settle onto the adhesive.

In witness whereof, I hereunto subscribe my name this 26th day of December A. D, 1922.

JOHN BERTRAND JOHNSON. 

